Wagner’s Tristan und Isolde scandalized and fascinated audiences when it first appeared in 1865 while revolutionizing music.

There are few single works of art that have had such a profound cultural impact. This concert staging of Act II revealed why – nearly a century-and-a-half on, the music still has the power to entrance and disturb in equal measure.

The most important character in Wagner’s mature operas is the orchestra, which through the intricate web of Wagnerian leitmotifs recalls, anticipates, contextualizes and comments on the action. The LPO played its role in masterly fashion under principal conductor Vladimir Jurowski.

The crucial offstage horn calls which open the act exploited Symphony Hall’s acoustic to magical effect. So did having Brangäne, a splendidly passionate Sarah Connolly, sing her warning to the oblivious lovers from high up near the organ – suggesting the opera’s two different worlds of day and night.

This was a flawless cast with Anja Kampe’s Isolde having the necessary vocal power and ardour but without sacrificing warmth, femininity and suggestive depths of erotic allure – Wagner demands all that from his heroine. The American tenor Robert Dean Smith, a Bayreuth Tristan, projected Wagner’s alliterative text in exemplary style. And the couple’s hymn to love was immensely powerful.